A numerical model of front fired BTPS boiler is taken up to study the changes in combustion characteristics due to the quantity and composition of minerals in coal. There is a lot of scope for improving the present model. Yet, first of all it establishes the need for such studies in India and secondly it adds to our current understanding of the behaviour of mineral matter during combustion. In place of a fixed value, specific heat of coal is fitted with a polynomial the coefficients of which were determined from the mineral composition of the coal. The emissivity of the particle similarly is not a fixed value but modified with a user defined function. User defined functions have been developed for thermal conductivity and porosity of the particle however they could not be put to use as the CFD software only permits a fixed value for thermal conductivity and porosity of the particle.